The Effects Of Lineup Style And Instructions On Eyewitness Accuracy And Confidence

Eyewitness misidentifications are the leading cause of known wrongful convictions (The Innocence Project, 2012). System variables like instructions at the time of a lineup presentation and lineup style can impact both eyewitness confidence, which can be measured as average confidence and perpetrator confidence, and accuracy. However, very few studies have combined these system variables to test accuracy and confidence. Charman, Carol, and Schwartz (2018) introduced a novel measure of average confidence with the typical perpetrator confidence measure to gather data from both choosers and non-choosers. The current study extended Charman et al.’s (2018) study that looked at one system variable, instructions, and its effect on both types of confidence. I examined the impact of two system variables, instructions and lineup style, on both measures of eyewitness confidence and accuracy. In my study (N=180), I found that participants in the simultaneous lineup condition were the most accurate (59.21%) compared to the sequential condition and those in the simultaneous and biased instruction condition were more accurate (72.22%) than all other conditions. No significant differences were found for effects on eyewitness confidence.